The first anxiously awaited attempts are being made to salvage the stricken cruise ship Costa Concordia in the biggest operation of its kind.

An international team of engineers are working to right the luxury liner, which capsized after striking a reef in 2012 killing 32 people.

Engineer Sergio Girotto said the lifting began three hours late this morning after being delayed by an unexpected thunderstorm.

The storm pushed back the positioning of a barge hosting a floating command room centre. There, engineers using remote controls will guide a synchronised leverage system of pulleys and counterweights to delicately nudge the ship free from its rocky seabed perch.

The operation is a proven method to raise capsized vessels, but the Concordia has been described as the largest cruise ship ever to require the complex rotation.

The goal is to raise the Concordia from its side by 65 degrees to vertical for eventual towing.

Asked how long it would take for people on shore to see the ship making significant movement towards the vertical, Mr Girotto said that “after a couple of hours, you should be able to see something visible from a distance”.

The first couple of hours will be critical, engineers predicted. Pieces of the granite seabed are embedded in the submerged side of the hull, which divers have not been able to fully inspect.

The operation was supposed to begin before dawn, but daylight broke even before the barge carrying the engineers close to the ship could leave shore. After the storm blew away, seas were calm.

Engineers have dismissed as a “remote” possibility the chance that the Concordia might break apart during rotation and no longer be sound enough to be towed to the mainland to be turned into scrap.

Costa Crociere, the Italian unit of Miami-based Carnival, is picking up the tab for the operation and its intricate preparation. The company puts the costs so far at 600 million euro (£500 million), though much of that will be passed on to its insurers.

The operation, known in nautical parlance as parbuckling, was used to raise the USS Oklahoma in 1943 after the Japanese attack on Pearl Harbour - though the Concordia is far larger.

The reef sliced a 230ft gash into what is now the exposed side of the Concordia’s hull, letting seawater rush in. The resulting tilt was so drastic that many lifeboats could not be launched.

Dozens of the 4,200 passengers and crew were plucked to safety by helicopters or jumped into the sea and swam to shore. Bodies of many of the dead were retrieved inside the ship, although two bodies were never found and might lie beneath the hulk.

The Concordia’s captain is on trial on the mainland for alleged manslaughter, causing a shipwreck and abandoning the ship during the chaotic and delayed evacuation. Captain Francesco Schettino claims the reef was not on the nautical charts for the liner’s week-long Mediterranean cruise.